Device for preparing elemental carbon enriched in carbon-13

ABSTRACT

Apparatus for use in preparing elemental carbon comprising a tubular member having an apertured wall portion separating the member into first and second chambers with means disposed on said apertured wall portion to facilitate passage of a fluid released from first chamber into second chamber and impede return of the fluid to the first chamber.

United States Patent [191 Liner [4 1 Mar. 12, 1974 DEVICE FOR PREPARINGELEMENTAL CARBON ENRICHED IN CARBON-l3 [76] Inventor: Jerome C. Liner,1430 Beaverton, Cincinnati, Ohio 221 Filed; Feb. 23, 1972 [21] Appl.No.: 228,615

[52] 1 US. Cl..... 23/2595, 23/252 R, 23/264,

23/294, 423/445, 423/458, 423/459 7 [51] Int. Cl Cl0b 57/00 [58] Fieldof Search. 55/440, 158, 420;

[56] I References Cited 1 UNITED STATES PATENTS 3,690,846 9/1972Shin-ichi Akai et al. 23/294 2,705,186 3/1955 Hardy et al. 23/ 294 X9/1939 Lambert et al 55/440 X OTHER PUBLICATIONS Isotopic Carbon byMelvin Calvin, John Wiley Sons, Inc.; New York 1949 p. 116..

Primary Examiner -Morris O. Wolk Assistant Examiner-Arnold TurkAttorney, Agent, or FirmJohn A. Horan; Ignacio Resendez [57] ABSTRACTApparatus for use in preparing elemental carbon comprising a tubularmember having an apertured wall portion separating the member into firstand second chambers with means disposed on said apertured wall portionto facilitate'passage of a fluid released from first chamber intosecond'chamber and impede return of the fluid to the first chamber.

3 Claims, 5 Drawing Figures PATENTEBIAR 12 2974 FIG.

FIG. 3

IRON FILINGS FIG. 4

- IRON CHLORIDE REDUCTION -IOOO C ARGO" SUBLIMATION HCI sAs CARBON l3-DEVICE FOR PREPARING ELEMENTAL CARBON ENRICHED IN CARBON-13 BACKGROUNDOF INVENTION A problem exists in fulfilling industrial and researchneeds for elemental carbon-l3 C). This problem is a result of anunavailability of a method and equipment to provide efficient andquantity production of C. Although carbon-l3 enriched chemical compoundare readily available, such as methane, carbon dioxide or bariumcarbonate, each containing about 90 percent carbon-l3, the elementalform of carbonl3 is more difficult to obtain. I I

A typical process for preparing elemental carbon-l 3 may involve placingiron particles or filings in a porcelain boat in a quartz reaction tube,and then passing carbon dioxide enriched in carbon-l3 and hydrogen intothe reaction test chamber. Contact of the gases with the iron particlesresults in a reduction of the carbon dioxide to elemental carbon on topof the iron. Gaseous hydrogen chloride is thereafter flowed into thereaction chamber and forms ferrous chloride which then sublimes out ofthe porcelain boat and out of the reaction chamber.

This process has several disadvantages including being restricted tovery small quantities of elemental carbon being produced, back diffusionof ferrous chloride which substantially decreases the purity of theelemental carbon, and the requirement of several passes of hydrogenchloride gas for sublimation and removal of the iron chloride.

SUMMARY OF INVENTION In view of problems and disadvantages such asoutlined above, it is an object of this invention to provide anapparatus that yields efficient and greater quantity conversion ofcarbon-l3 contained in carbon dioxide enriched in carbon-l3 to elementalcarbon-13.

- It is an object of this invention to provide an apparatus which yieldsrelatively large quantities of high purity elemental carbon-l 3 product.

It is an object of this invention to provide an apparatus whichminimizes or impedes back diffusion of ferrous chloride. I

Various other Objects and advantages will appear from the followingdescription of the invention and are particularly pointed outhereinafter in connection with the appended claims. Various changes indesign, materials, etc., as described herein may be made by thoseskilled in the art without departing from the scope and principles ofthis invention as brought out in the appended claims.

The invention comprises an enclosure separated by' DESCRIPTION OFDRAWING.

FIG. 1 is a partly cross-sectional view of one embodiment of thisinvention.

FIG. 1a is an enlarged cross section of conduit 17 of FIG. 1.

FIG. 2 is a partly cross-sectional view of one embodiment of a devicewhich may be used for the reduction of carbon dioxide to elementalcarbon.

FIG. 3 is a cross-sectional view of a preferred embodiment of thisinvention.

FIG. 4 illustrates a preferred processing sequence for conversion ofcarbon-13 in carbon dioxide or carbon monoxide to elemental carbon-l3.

DETAILED DESCRIPTION FIG. 1 illustrates one embodiment of this device10. In FIG. lithe elongated generally tubular housing or member 11,which may be made of quartz or any other suitable material, hastransversely disposed therein an apertured wall portion 12 which formswith the tubular member separate first and second chambers 14 and 13respectively. Member 11 may have disposed at either end connecting means15, such as a balljoint, so as to incorporate device 10 in a processingsequence. Disposed over, in alignment and in communication with theaperture 16 of wall portion 12, and extending therefrom and projectinginto and terminating within a downstreamor second chamber 13, is anopen-ended, restricting conduit means 17, as shown in FIG. 1a, designedto facilitate passage of, or to conduct, released fluids (not shown)from first or upstream chamber 14 into second or downstream chamber 13,and to prevent, impede or retard return of this product or flu-.

ids from second or downstream chamber 13 to first chamber 14. It hasbeen found that a suitable means 17 comprises a capillary or smalldiameter tube with a passageway 26 (shown in greater detail in FIG. 1a)of from about 1 mm to about 3 mm inner diameter which also has agenerally U-shaped configuration with open end disposed toward wallportion 12 in said second chamber 13, with the tube 17 having a radiusof the arc of the U-shaped portion of the conduit of about 10 mm andextending about 40 mm into second chamber 13. Means 17 includes an inletportion 28 communicating through aperture 16 with Chamber14 and anoutlet portion 27 communicating with chamber 13 disposed by said U-shapein a direction opposite to the normal flow of process gas throughchamber 13. The geometrical configuration of the capillary tuhegenerally aids in preventing or impeding return of released product intofirst chamber 14. The device 10 is: used in a generally horizontalposition so as to enable the particles 19 dis posed in chamber 14 toremain positioned on the side and not interfere with passageway of means17. Means 17, in effect, acts as a onewayvalve allowing passage offormed gas but effectively preventing its return. A suitable coolingmeans 20, such as a water jacket, may

be disposed adjacent to and generally surrounding second chamber 13. Thecooling means may condense the fluids or products released from firstchamber 14 subsequent to passage through aperture 16 and conduit ormeans 17 so as to assist in preventing or impeding return of the productto first chamber 14 through conduit or means 17.

FIG. 2 is a partly cross-sectional view of a device 30 which may be usedwith this invention as will be de-.

scribed below. In FIG. 2, generally tubular housing or member 31 mayhavea sintered glass wall portion 32 with pore size ranging from aboutmicrons to about 200 microns which may separate the tubular member 31into two separate chambers a first'or upstream chamber 34 anda second ordownstream chamber 33.

Sintered glass wall portion 32 prevents passage of particles (such asparticles 35) greater than about 200 microns into chamber 33. Member 31also may have disposed at either end connecting means 36, similar tomeans in FIG. 1, to interconnect body 30 in a processing sequence.

As shown in FIG. 3, a variation of embodiment 10 may also include asintered glass wall 21 disposed intermediate said apertured wall portion12 and first chamber 14 with similar pore openings as above. A benefitfrom such an embodiment as shown in FIG. 3 would be to prevent elementalcarbon particles 19 or other particles from passing through or cloggingaperture 16 and means 17 as will be more fully described below. Sinteredglass wall 21, like glass wall portion 32, may be made from any suitablematerial and has micron size pores ranging from about 90 microns toabout 200 microns so as to effect blockage of particles yet allowpassage of fluids.

FIG. 4 illustrates a preferred processing sequence for obtainingcarbon-l3 from carbon-l3 enriched carbon dioxide or carbon monoxide. Asshown in FIG. 4, the conversion of carbon monoxide or carbon dioxideenriched in carbon-l3 to elemental carbon-13 may be accomplished byfirst disposing iron filings or particles in chamber 14, or in chamber34 using the device of FIG. 2. Another embodiment for this purpose isshown in FIG. 3 which combines wall portion 12 of FIGS. 1 and sinteredglass wall portion 32 of FIG. 2. The chamber 14 (or 34 if embodiment ofFIG. 2 is used) is heated to and maintained at about 600 C. Carbon-13enriched carbon monoxide or carbon dioxide and hydrogen are passed intothe desired reaction chamber which contains the iron filings. There maybe a slight mole excess of hydrogen in the gas intermixture and areduction to elemental carbon and water may be initiated and carriedout. A constant pressure of carbon dioxide or carbon monoxide andhydrogen may be maintained in the reaction chamber at a partial pressureof about 500 Torr and 300 Torr respectively, for 4-6 hours. As elementalcarbon is formed, methane formed in the reaction may be removed throughchamber 13 (or chamber 33 if device 30 is used) by any suitable means,such as a cryogenic trap (not shown), and stored or reprocessed forsubsequent conversion to elemental carbon.

The device 30 of FIG. 2 including first chamber 34 may be desirable forthis initial reaction primarily because of ease of processing since gasflow and removal may be facilitated. If desired, the embodiment of FIG.1 may be used. After conversion to elemental carbon, the iron particleshaving the elemental carbon thereon may be removed from first chamber 34of the embodiment 30 of FIG. 2 and disposed within first chamber 14 ofthe device 10 of FIG. 1. If the conversion to elemental carbon wasconducted in first chamber 14 of FIG.

l, removal may not be required. The embodiment illustrated in FIG. 3incorporating sintered glass wall 21 may be used for both process stepsand would likewise not require removal of the carbon layered ironfilings. Anhydrous hydrogen chloride gas may then be introduced into thereaction or first chamber 14 to react with the iron to form ferrouschloride which may sublime out of first chamber 14 through means 17 intosecond chamber 13 wherein condensation occurs. Removal of ferrouschloride from chamber 14 is effected by gaseous pressure such as fromhydrogen chloride which may be introduced at the rate of about I cc perminute with about 180cc per minute of argon or other inert gas. Argon ispreferred because it is relatively inexpensive yet is heavy enough toreadily sweep the ferrous chloride from the chamber. The reactionchamber 14 is generally maintained at about I,OOO C by appropriateheating means 29, such as a heating coil or burner (showndiagrammatically by burner 29), during this reaction. The reaction maycontinue until ferrous chloride is no longer sublimed. Means l7 preventsthe return of the ferrous chloride and thereby results in an elementalcarbon-l 3 product of high purity. The generally U-shaped, or othersimilar configuration, feature of means 17 facilitates removal ofproduct from first chamber 14 into second chamber 13 but not in reversefashion. In FIG. 3, sintered glass wall 21 prevents the loss ofelemental carbon particles. The tubular member 11 may then be flushedwith argon and cooled to permit recovery of the elemental carbonenriched with carbon-l 3. I

' Using the device shown in FIG. 2 for the first reaction, i.e., thedeposition of elemental carbon on the iron particles or filings, and thedevice of FIG. 1, which is the subject matter of this invention, for thesublimation of the iron particles, 30 to 40 gram batches of carbon-13have been successfully produced. Larger recovery rates and batch sizesare limited only by the size and capacity of the apparatus used.

The device presented herein solves prior large quantity productiondifficulties and lack of purity problems while at the same time itenables efficient, quantitative recovery of high purity elemental carbonenriched in carbon-l 3.

What is claimed is:

l. A device for conversion of carbon-I 3 contained in carbon dioxideenriched in carbon-13 to elemental carbon-l3 comprising an elongated,horizontal, generally tubular'member having an open inlet mouth and anopen outlet mouth, an apertured wall portion disposed transversely ofsaid tubular member intermediate said open mouths and forming with thetubular member separate first heating chamber and second coolingchamber, and a generally U-shaped open-ended restricting conduit ofinterior diameter of from about I mm to about 3 mm in communication withthe aperture of said wall portion and projecting into and terminatingwithin said cooling chamber with said open end disposed towards saidapertured wall portion, said conduit conducting fluids from the firstchamber to the second chamber and impeding return of fluids from saidsecond chamber to said first chamber, and cooling means adjoining saidcooling chamber and spaced from said first chamber and said U-shapedrestricting conduit to cool said fluids subsequent to passage throughsaid conduit.

2. The device of claim 1 wherein said conduit extends about 40 mm intosaid second chamber and the radius v of the arc of the U-shaped portionof the conduit is about 10 mm.

3. The device of claim 1 wherein a sintered glass wall portion isdisposed intermediate said apertured wall portion and first chamber,with pores therein of size of from about microns to about 200 microns.

' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,796Dated March 12, 1974 I fl Jerome C. Liner It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

after [76] add:

--[73] Assignee: The United States of America as represented by theUnited States Atomic Energy Commission Signed and sealed this 23rd dayof July l9? I (SEAL) Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents F -10 (10- USCOMM-DC we're-Pm 9 U.S. GOVERNMENT PRI NTUIGOFFICE: I," 0*3I33,

2. The device of claim 1 wherein said conduit extends about 40 mm intosaid second chamber and the radius of the arc of the U-shaped portion ofthe conduit is about 10 mm.
 3. The device of claim 1 wherein a sinteredglass wall portion is disposed intermediate said apertured wall portionand first chamber, with pores therein of size of from about 90 micronsto about 200 microns.